Convection heater



Aqg. 27, 1946. B splETl-l l 2,406,643 com/ECTION HEATER A Filed sept. 2, 1943 4V2 sheetysheetl 1 y 'lllllllllll/A m; u @a Aug. 27,1946. B. SPIETH' 42,406,643

i coNvEcTIoN HEATER Filed Sept. 2, 1943 2 SheetsSheet 2 l y incliner-s of' rig. 2;, Y

Fig. 7 is anenlarged'fragmental verticalv cross Patented Aug. 27, 1946 UNITED STATES PATENT OFFICE;

CONVECTION HEATER Benjamin Spieth, Racine, Wis., assignor to-Modine Manufacturing Company, Racine, Wis., a corporation of Wisconsin 2, 1943,'seria1 No. 500,877

Application September zolaims. (01.257-1'36) This invention relates to a convection heater. One object of the invention is to provide a cabinet having an air inlet opening at its bottom and a hot air outlet opening at its top, together with arheat transfer element disposed adjacent the open bottom of the cabinet and adapted to heat air passing upward through the cabinet.

Another object is to provide a damper controlled auxiliary air inlet to the cabinet of the heater and disposed above the heat transfer element whereby the heat output of the cabinet may be variedr from a maximum to a value approachin'g zero.

Another object is to provide an auxiliary air inlet to the cabinet protected by a grille, together with a damper to regulate the volume of air entering the auxiliary air inlet, the damper being so mounted thatit may close the grille when in one extreme position and permit an unrestricted flow Vof air through the hea'tingiele-` 'ment and cabinet, or it may cover the heating section wholly or in'part in` other positions and permit an unobstructed flow of air through the auxiliary air inlet, together with meansfor adjusting the damper to'any desired position between its two extreme positions. i Y Another obj ect is to provide a convection heater vthat can be constructed economically and with a minimum number of parts and one that is highly efcient in operation.

Withthese and other Aobjects and advantages in view, this invention consists' in the several novel features hereinafter fully described and claimed.

One embodiment of the invention is illustrated in the drawings accompanyingthis specification nwhich:

vFigiY is a front elevation of the heater; Fig. 2" is a vertical crosssection taken on the line ..2-2 oflig. l; ,.Fig'. 43v is a vertical longitudinal section taken theline 3+3`of Fig. 2, andshowing part of the heater broken away.A Figs.V 2 and 3 are upon zi-slightly enlarged scale; 1 Fig. .4 is an enlarged' takenon; the- -lineflIf-A of Fig.; 2,. illustrating the y(italianer contrcllingmechanism and a fragment of thedrlpertself; i 'v Fig. 5 is a vertical cross section ofthe damper .controlling mechanism and damper showing the lattenin its closed position with respectto the auxiliary air-inlet; I

Fi`g.j6i's` a 'detail' horizontal section taken on detail horizontal section section through the front wall and damper illustrating the hinge connection between them; and

Fig. 8 is an enlarged fragmental verticalcross section through a certain indicator blade and plate used in connection with the damper.

`Referring to said drawings,r which are merely illustrative of one embodiment. of lthe invention, the reference character I0 designates the cabinet ofr theheater, which is desirably rectangular in form and composed of sheet metal. Conveniently the cabinet may compriseV a front wall II having rearwardly extending flanges I2 at its side edges, and a rear wall I3 formed with forwardly extending side wall flanges I4 that overlapy the front wall flanges and are secured 'thereto in any desirable manner, i i

One form of securing means between the overlapping side wall flanges I2-I4 is illustrated in Figs. 2 and 6 and comprises L-shaped brackets 9, one spot welded or otherwise rigidlyv secured toe'ach side wall flange I4 and formed with a flanged arm 8 which r bears against the inner face ofthe front wall. Bolts and nuts 'Ilmay be employed for fastening the front wall vto -the bracketsV 9. Shoulder rivets |50'l secured to the flanges Iland extending through notches in the flangesl I2, may be employed for fastening together ,the lower ends of the front and back setions of the cabinet. 1 ve' The metal sheet that forms the front wall H may be of greater length than that required to form the front wall, and its upper end may be bent rearward to extend in an inclined direction and form the top wall I la of the cabinet. The

- top wall is provided with an air outlet opening I5 which is protected by a grille l5. Conveniently the grille I6 may comprise angle iron members IBa spot welded or otherwise rigidly secured to the top wall adjacent the front and rear edges of the ,opening therein, and spaced bars IBb intermediate lthe angle iron membersand rods or Wires-IBC that extend through the angle iron members fand bars. The metal which forms the topwall [I a is bent downwardly at thel side edges of the top wall to form flanges I2a` that are'in eect continuationsof the flanges I2 of the front wallland overlap the side wall flanges I4 as is seen at IZUinFig. `3. At the places where the flanges I2V and Iza- I4 overlap each other the side wall ang'es I4 are, offset inwardly to receive the overlapping portions of the anges I2 and I 2a',`whereby the outer faces of the side walls may be hush. The rear end of the top wall maybe bent downwardly to provide an upright flange I Ib that extends contiguously with. the inner face of the rear wall I3, and an air seal llc may be provided at the upper inner corner of the cabinet. For reinforcing the front wall a horizontally extending V-shaped reinforcing member lila may be spot welded or otherwise secured to the inner face of the front wall.V The rear wall may be re inforced with horizontally extending channel bars 13a, riveted or otherwise fastened to the rear wall. Conveniently the heater is supported above the oor of the room in which it is contained by mounting it on a wall of the room by bolts which pass through the channel bars i3d. A sheet of heat insulating material 13b may be secured to the outer face of the rear wall to prevent an excess amount of heat from radiating from the rear wall.

Adjacent the open bottom of the cabinet is a heat transfer element I1 which is supported from the side walls of the cabinet, and in the present embodiment of the invention the heat transfer element comprises a plurality of parallel fluid conducting tubes I8, l8a headers Ill-20 connected to the ends of the tubes and heat radiating fins 2 I--22 through which the tubes extend. The headers are of particular construction and are more particularly shown and described in my copending. application Serial No. 500,876, filed ySeptember 2, 1943, to which reference may be had for a fuller description.

Briefly, each header comprises a seamless tube of` suitable dimensions of octagonal, hexagonal or other vmany-sided configuration. The bore 23 of the header is cylindrical and the wall thereof is threaded at Vboth ends for the reception of a pipe fitting 24 or 24a or a screw plug 25 or 25a. Holes are drilled in the sides of each header for connection with the ends of the tubes. The several parts of the heat transfer element may be brazed together or otherwise integrally united in accordance with the common practice.

Asillustrated, the heat transfer element is intended for use in a two pipe heating system. The elbow fitting 24 connects with a steam or hot water supply p-ipe 28 and the elbow tting 24a connects with a return pipe 30. If desired an air valve 31 may be provided at the discharge end of the heat transfer` element and in that event the screw plug a at the discharge end may be drilled and tapped for the reception of the threaded nipple of the air valve. v

For giving additional support to the headers, the endV fins 2l are preferably constructed of heavier gauge metal than the intermediate fins 22, and the lower ends of these end fins extend at right angles to the main upright parts 33 thereof to provide horizontal flanges 34 which are formed with holes for the reception of the lower ends of the headers. i

Secured to the side walls I4 of the cabinet and extending from the front wall to the back wall, arebracket members 35 which are formed with oppositely directed upright portions 35v and 31 bent at right angles to their horizontal portions 3B. The upright portions 36 are contiguous with l the side walls of thevcabinetvand are rigidly secured thereto as by spot welding or otherwisejand the upright portions at 31 are spaced inwardly from the side walls a distance somewhat greater than the diameter of the headers, and the lower ends of said upright portions 31 of the bracket members are 4bolted orotherwise rigidly secured to the upper ends ofthe end ns 2| of the heat transfer element as by bolts and nuts 39.- The inward spacing of the upright portions 31 of the bracket members provides space for the reception of the headers close to the side walls of the cabinet and also provides a confined passageway for the ascending heated air that rises from the heat 5 transfer element.

In the front wall H of the cabinet, directly above the heat transfer element, is an auxiliary air inlet 4U which is protected by a grilled! that extendsl across the opening, directly behind it. Desirably the grille may comprise horizontal angle Y iron bars 42, intermediate bars 43 and vertical rods or tubes 44 extending'through said bars. The horizontal flanges of the angle bars 42 are coincident withthe upper and lower edges of the auxiliary air inlet. Upright bars 45 that are coincident with the side edges of the auxiliary air inlet connect the angle iron bars 42 and together with said angle iron bars provide a throat which extends inwardly from the marginal edges of the auxiliary air inlet. The` grille is fastened to the inner face of the front wall by spot welding the angle iro-n bars 42 thereto or by any other suitable fastening means.

For regulating the volume of air admitted to the cabinet through the auxiliary air inlet, a damper 43 is provided for closing or partially closing the auxiliary air inlet or forleaving said inlet entirely free and clear for the unrestricted flow of air therethrough, I

Desirably the damper is in the form of a rectangular piece of sheet metal having one section 41 thereof bent at a slight angle to the main section 48. The damper is hingedlyconnected on a horizontal axis to an angle shaped hinge plate 49 which is spot welded or otherwise secured to the front wall of the cabinet, Cooperating with said hinge plate 49 is a hinge plate 50 secured to the inner or under side of the damper. The adjacent ends of both of these hinge plates are curled to form hinge ears 5| through which extends a hinge pin 52. The damper is of such dimensions that when closed over the auxiliary air inlet the main section 48 covers the auxiliary air inlet grille 4I thereby excluding the 'admission of air through the auxiliary air inlet and when fully opened to its other extreme position the'damper closes or substantially closes the hot air passage between the inwardly spaced parts 31 of the bracket members 50 35 and the front and rear walls of the cabinet.

The rst mentioned position of the damper is illustrated in Fig. 5 and its second mentioned position isillustrated in dotted. lines in Fig, 2. The damper may assume any position'intermediate these extreme limits, one such position being illustrated in solid linesVV in Fig. 2.

For adjusting the damper and holding it in any position of adjustment, damper controlling means have been provided which conveniently may comprise a threaded stem 53 having a swiveled connection with thefront wall of the cabinet and being threadedly engaged in a trunnion nut 54 which is provided with trunnions 55 that are swiveled in bracket arms 5S, bolted or otherwise l secured to the damper as by bolts and nuts 51.

.75 .swiveled in sockets 63 that may be formed by striking up the metal of the front wall and the hinge plate 49 to form semi-circular depressions which when matched up provide cylindrical bearings for the trunnions. The metal of the front wall and hinge plate between the struck up portions is cut away for the reception of the trunnion bearing 6|. A knob or handle 64 is secured upon the outer extremity of the spindle 60 as by Va screw 65. The threaded stem is held against longitudinal movement with respect to the trunnion bearing by the knob on one side and the shouldered end of the threaded stem on the other side.

For indicating to an attendant the various positions of the damper, an arcuate indicator blade 66 is provided which has a flat portion 61 that is inserted between the damper 4B and the flanges 59 of the bracket arms 58 and secured thereto by the bolts and nuts 51. An arcuate indicator plate 68 having suitable indication marks thereon is secured upon the external face of the indicator blade 66 and cooperates with one of the grille bars 43a to indicate the position of the damper.

In the operation of the heater a fluid heating medium such as steam or hot water is supplied to the heat transfer element and air entering the open bottom of the cabinet becomes heated as it passes the heat transfer element, and rises in the cabinet when the damper is in its position closing the auxiliary air inlet or in any of its intermediate positions, and discharges through the outlet opening in the top of the cabinet.

If it is desired to have an unrestricted flow of hot air through the cabinet, the damper regulating knob B4 is turned in the proper direction to swing the damper into the closed position seen in Fig. 5, wherein the damper completely closes the passage through the auxiliary air inlet. With the damper located in the closed position just described, a maximum heat output is obtained.

If it is desired to reduce the heat output to a value approximating zero, the damper controlling knob is turned in the proper direction to swing the damper into the position shown in dotted lines in Fig. 2y wherein it practically closes the passageway through the cabinet at a place directly over the heat transfer element, and at the same time completely uncovers the auxiliary air inlet, permitting an unrestricted flow of cooler air into the cabinet, which is heated slightly by heat radiated from the damper, and rises through the cabinet, finally discharging from the outlet opening in the top thereof.

Having thus described my invention, it is obvious that various immaterial modifications may Abe made in the same without departing from the spirit of my invention; hence I do not wish'to be understood as limiting myself to the exact form, construction, arrangement and combination of parts herein shown and described, or uses mentioned.

What I claim as new and desire to secure by Letters Patent is:

1. A convection heater comprising in combination a cabinet having an air inlet opening, an air outlet opening and an auxiliary air inlet intermediate the air inlet and air outlet openings and spaced from said air inlet opening, oppositely disposed bracket members rigidly secured to the side walls of the cabinet and formed with inwardly spaced depending portions, a heat transfer element having iins thereon, the endmost ones of which are secured to said depending portions of the bracket members and together with said bracket members divide the lower part of the cabinet into a heating chamber :and two end chambers, the heat transfer element having heating tubes in said heating chamber and headers in said end chambers, and a pivotally mounted damper extending between said inwardly spaced depending bracket portions and arranged in one position to close the auxiliary air inlet, and arranged in another position to close the passageway between the depending portionsv of the bracket members, said damper having means for adjusting it to any position between its limits of movement'.

2. A convection heater comprising in combination a cabinet having an air inlet opening at the bottom and an air outlet opening at the top and an auxiliary air inlet in the front wall of the cabinet intermediate said inlet and outlet openings, bracket members rigidly secured to the side walls of the cabinet and being formed with depending portions spaced inwardly from the side walls, a heat transfer element in the cabinet below said bracket members and having headers disposed in the spaces between the side walls and the depending portions of the bracket members, said heat transfer element having also fluid conducting tubes connecting said headers and extending in the space between said depending portions of the bracket members, and L-shaped ns secured to said tubes and to said depending portions of the bracket members, and being formed with horizontal apertured flanges in which the headers are held, said depending portions of the brackets and L-shaped ns dividing the lower part of the cabinet into a heating chamber for the tubes and end chambers for the headers, and a damper extending between said depending inwardly spaced portions of the brackets and pivotally mounted on an axis disposed adjacent the lower edge of the auxiliary air inlet.

BENJAMIN `SPIETH- 

